There are known designs for positive locking of the adjustable part in a support bearing fastened to the body with teeth on one part of the steering column, mostly on the adjustable part, and with a locking member that can be moved via an actuating device, possibly against the force of a spring biasing the locking mechanism in the locked position with complimentarily designed teeth.
However, positive-locking mechanisms consisting of meshing teeth on parts that are adjustable axially relative to one another can be adjusted only in finite positions. Nevertheless, they offer the advantage of snap locking, so that it is possible to transmit strong forces, which might lead to slip in the case of friction clamping, in the axial direction. Positive locking is therefore preferable in steering columns for absorbing strong forces occurring during crashes.
An essential disadvantage of such positive locking is, however, the inevitable "tip-over-tip" position of the meshing teeth on the two parts of the steering column, which are axially adjustable relative to one another. Such a position, in which interlocking cannot be guaranteed, cannot be avoided with certainty even if the tips of the teeth are of a pointed design. Locking and consequently defined catching can be achieved in such a case only by repeated pressure on the adjustable part, i.e., for example, the steering wheel. This may give rise to unfavorable effects which are unacceptable in a vehicle for safety reasons. After the alleged locking of a newly set position of the steering wheel, a lifting movement by half the pitch of the teeth of the locking members becomes established, which suggests free movement to the driver of the motor vehicle, who might interpret this as a malfunction. The "tip-over-tip" position during a crash occurring immediately thereafter can lead to slipping of the teeth, because no appreciable lifting movement leading to locking will occur because of the inertias of all the components involved in the catching.